- Copper(i)-catalysed asymmetric allylic reductions with hydrosilanes
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A copper(i)-catalysed asymmetric allylic reduction enables a regio- and stereoselective transfer of a hydride nucleophile in an SN2′-fashion onto allylic bromides. This transformation represents a conceptually orthogonal approach to allylic substitution reactions with carbon nucleophiles. A copper(i) complex based upon a chiral N-heterocyclic carbene (NHC) ligand allows for stereoselectivity reaching 99% ee. The catalyst enables a stereoconvergent reaction irrespective of the double bond configuration of the starting materials.
- Thanh Nguyen,Thiel, Niklas O.,Teichert, Johannes F.
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supporting information
p. 11686 - 11689
(2017/11/03)
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- Copper-Catalyzed Regioselective Hydroalkylation of 1,3-Dienes with Alkyl Fluorides and Grignard Reagents
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Copper complexes generated in situ from CuCl2, alkyl Grignard reagents, and 1,3-dienes play important roles as catalytic active species for the 1,2-hydroalkylation of 1,3-dienes by alkyl fluorides through C-F bond cleavage. The alkyl group is introduced to an internal carbon atom of the 1,3-diene regioselectively, thus giving rise to the branched terminal alkene product. Making the switch: A copper-hydride species, generated by the treatment of a copper salt with alkyl Grignard reagents, catalyzes the 1,2-hydroalkylation of 1,3-dienes by alkyl fluorides and Grignard reagents. The alkyl group of the alkyl fluoride is selectively introduced to an internal carbon atom of the 1,3-diene and the Grignard reagent acts as hydride source to give the branched terminal alkene, even in the presence of alkenes and alkynes.
- Iwasaki, Takanori,Shimizu, Ryohei,Imanishi, Reiko,Kuniyasu, Hitoshi,Kambe, Nobuaki
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p. 9347 - 9350
(2015/08/06)
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- An alternative regioselective ring-opening of epoxides to chlorohydrins mediated by chlorotitanium(IV) reagents
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A regioselective cleavage of various epoxides to vic-chlorohydrin isomers by using TiCl4 or TiCl4-Ti(O-i-Pr)4 complex was investigated. The less substituted alcohols, C2-attack products, were formed by the use of TiCl4 in CH2Cl2. On the other hand, the less substituted chlorides, Cl-attack products, were formed by using TiCI(O-i-Pr)3 in DMF. These regioselectivities depend on both the acidity of the Lewis acids and the polarity of the solvents.
- Nishitani, Kiyoshi,Shinyama, Kyoko,Yamakawa, Koji
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p. 191 - 197
(2008/09/17)
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